Regions
Northwest Coastal.
Avalanche danger is increasing as the new storm moves in from the Southwest.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Light snow (5-8 cm) overnight and continued light snow during the day on Friday. Strong Southeast winds overnight becoming moderate Southeast during the day on Friday. Freezing levels at or near valley bottoms on Friday. 10-20 cm of new snow by Saturday morning with another 15-30 cm during the day combined with very strong Southerly winds and freezing levels rising up to about 1200metres. Another 10-15 cm of new snow by Sunday morning and snow continuing throughout the day.
Avalanche Summary
No new avalanches reported. The forecast new storm is expected to increase avalanche activity over the next few days.
Snowpack Summary
The new storm is expected to develop a storm slab above the recent "dusting" of new snow that is sitting on a variety of surfaces which include wind slabs in alpine terrain, hard rain crusts at lower elevations and weak surface hoar crystals. Last week's heavy rain affected southern parts of the region up to alpine elevations, while the far north remained drier and sports a weaker snowpack in general. Areas which previously received rain have probably now formed a hard frozen crust. Upper elevation terrain and far northern areas are likely to have wind slabs and large fragile cornices. Deeper in the snowpack, weaknesses such as the mid-November crust-facet layer still exist. Avalanches at this interface have become unlikely, although the consequences of a release remain high. This layer may be more sensitive to triggering in steep, unsupported high alpine terrain, or in the far north of the region.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.